In recent years, organic semiconductor materials have replaced inorganic semiconductor materials as a working layer material in manufacturing new types of photovoltaic semiconductor elements. Compared to the conventional inorganic semiconductor elements, the organic semiconductor elements have the advantages of being light in weight, flexible, inexpensive, convenient to process, etc. In early stages, the organic semiconductors have energy conversion efficiency as low as 3%. However, the energy conversion efficiency of the organic semiconductors has been upgraded to the range from about 5% to about 10%. The organic semiconductors may be divided into two major types, namely, small-molecule semiconductors and polymer semiconductors. The small-molecule semiconductor elements must be inconveniently manufactured through the vacuum vaporization process. On the other hand, the polymer semiconductor elements may be conveniently and economically manufactured through solution process by way of spin-coating, inject printing, etc. to largely reduce the manufacturing cost of the semiconductor elements.
The traditional photo detector uses an inorganic material as its sensing material. It is expensive and uneasy to manufacture inorganic semiconductors by  doping silicon to enable different photo-detecting wavelengths. On the other hand, due to intrinsic properties thereof, the organic semiconductors can only detect lights in the ultraviolet and visible light ranges, and do not respond to light in the infrared range.
It is therefore tried by the inventor to develop an organic-semiconductor-based infrared receiving device, which has a transport layer with increased thickness to enable enhanced light absorbance, so as to increase the excitons formed at an interface between two combined predetermined semiconductor materials of the transport layer and thereby overcome the problem of low light absorbance of organic matters. In the organic-semiconductor-based infrared receiving device of the present invention, organic polymer semiconductors are used to absorb infrared light and generate photocurrent, allowing the infrared receiving device to be applied in the fields of distance sensing, bio-sensing, photo-sensing, etc.